Depending on the nature of the sprinkler system and the environment it is designed to protect, the system valve may be any of the following types: alarm valve ( "wet" system) , deluge valve ("wet", "dry" or "electric" systems), check valve ("wet" system), dry valve ("dry" system), dry differential valve ("dry" system) and control valve. Typically, the type of sprinkler system is selected during the design phase of the building which receives the sprinkler system. The type of sprinkler system selected dictates the type of system valve used.
While buildings typically remain useful for decades, it may become necessary to modify the sprinkler system in accordance with the evolving needs of the building. For instance, the building may initially be used as an office building. Such an office building typically includes a "dry" sprinkler system which employs a dry valve. After a significant period of years, the owner of the office building may decide to attract other clientele. For instance, the owner could convert the building to a facility for storing flammable products. In such an event, the original "dry" sprinkler system and dry valve would not provide adequate fire protection. Therefore, it would become necessary to convert the "dry" sprinkler system and dry valve to a "wet" sprinkler system and deluge valve for the purpose of insuring the safety of the building.
To convert the "dry" sprinkler system or a deluge valve and dry valve to a "wet" sprinkler system, it would be necessary to remove the dry or deluge valve from service and replace it with a wet valve. This process requires a significant period of time to accomplish, thereby increasing the overall cost of modifying the sprinkler system. Hence, a need has arisen for a modular system valve which can be readily field converted between an alarm valve, deluge valve, check valve, dry valve, dry differential valve and control valve.
As mentioned above, sprinkler systems often include a dry valve as the system valve. Some dry valves are problematic because the air pressure on the system side of the valve must be maintained at a relatively high level (e.g., 30-60 psi) in order to maintain the clapper in the closed position. Once the system is activated, the clapper is released from its closed position due to reduced air pressure within the system. Typically, the clapper is released before the residual air pressure within the system has decreased to the point where water can freely flow into the system (i.e., without being inhibited by the air pressure). Thus, the National Fire Protection Association (NFPA) requires such systems to include quick opening devices to assist in the exhausting of air so the water can freely flow into the system.
Even including such quick opening devices, the conventional dry valve-systems are generally slow acting to a fire condition. Hence, a need has arisen for a dry valve which is maintained in a set position by a relatively low air pressure within the system to enable the system to be more quickly filled with water upon actuation.
In addition, conventional deluge valves are problematic because they are slow to allow the lever to move from its latched position on the clapper. That is, such deluge valves typically include a diaphragm chamber which receives water or air pressure for causing a nose pin to engage and hold the lever in its latched position on the clapper. When the water or air pressure within the diaphragm chamber begins to decrease, the nose pin slowly moves away from the lever allowing the lever to slowly pivot away from the clapper. Hence, a need has arisen for providing an additional force to the nose pin to quickly move the nose pin from the set position to the activated position upon the activation of the system. Thus, there is a desire for a deluge valve which opens quickly in response to the activation of the system.
Conventional differential dry valves are cumbersome to reset after the system has been activated and the fire extinguished. That is, the entire sprinkler system must be shut down and the interior of the differential dry valve must be accessed to reset the valve. More particularly, once the differential dry valve is activated, the clapper pivots upwardly and is latched away from the valve seat to insure that it does not interfere with the flow of water therethrough. Once the fire has been extinguished, it is necessary to shut off the main supply of water, drain the water from the system and then access the interior of the differential dry valve to unlatch and reset the clapper. Accordingly, a need has arisen for a differential dry valve which can be reset without having to shut down the main supply of water and access the interior of the differential dry valve to reset the clapper.
None of the above-mentioned wet system valves include a flow switch within the valve body. Conventionally, flow switches are installed within the sprinkler system downstream from the system valve in one of the pipes. As such, it is necessary to purchase different size flow switches in accordance with the size of the pipe for which it is to be installed. Accordingly, a system valve which incorporates a flow switch within the body thereof, would enable one switch to fit all sprinkler systems and thereby reduce installation expense.
Some system valves may be controlled or accessed from the exterior of the building in which the valve is installed. Typically, such access is provided by the use of a wall indicator post. Wall indicator posts are typically designed to operate non-rising stem (inside screw) control valves, which are used to control the water supply to an automatic sprinkler, water spray deluge, foam-water deluge, or standpipe fire protection systems. Wall indicator posts permit operation of valves located immediately inside exterior walls while providing an exterior visual indication as to whether the valves are open or shut, in addition to a means for locking or sealing the valves in a particular position. Since wall indicator posts allow for valve operation from outside of the protected property, the opportunity for more prompt valve operation in an emergency situation is provided.
While conventional wall indicator posts are useful from outside the building, they are problematic in that they do not provide any ability to control the valve from within the building or to provide any interior visual indication as to whether the valve is open or shut. The ability to control the valve from within the building as well as to monitor the condition of the valve from within the building is particularly useful during an emergency situation. Hence, there exists a need for a valve and wall indicator post combination which would allow the valve to be controlled and monitored from both inside and outside of the building.
The most common type of check valve is a swing check valve consisting of a hinged clapper assembly mounted inside a pipe line. The clapper assembly generally includes a clapper and a clapper arm which suspends the clapper from the valve body. When there is no flow in the pipeline, the clapper of the assembly is maintained in a closed position. As fluid flows through the pipeline in the desired direction, the fluid pressure swings the clapper partially open. When fluid tries to flow in the undesired direction, the reverse fluid pressure presses the clapper shut, thereby stopping such flow.
In such conventional check valves, there is no intermediate position wherein the valve controls the degree of fluid flowing through the pipeline in the desired direction. To obtain a degree of control over the fluid flowing through the check valve, a control valve is installed in series with the check valve. Hence, to prevent back flow of fluid, it is necessary to use two valves. This increases costs since two valves must be purchased and installed. As such, there exists a need for a check valve which includes the further feature of being able to control the flow rate of the fluid flowing through the valve.
The present invention overcomes many of the disadvantages inherent in the above-described system valves by providing a modular valve which can be field converted between a wet configuration for a wet piping system and a dry configuration for a dry piping system. The dry differential valve of the present invention is of the low air pressure type which permits the sprinkler system to be quickly filled with water and opens relatively quickly. Moreover, the low air pressure dry valve of the present invention can be reset externally without disassembly, thereby saving time and effort. Further, the check valve of the present invention can function purely as a check valve or as a control valve to control the flow of water therethrough. In addition, the valve body of the present invention includes a flow switch thereby eliminating further installation expense of such a flow switch downstream from the valve. Consequently, use of the present invention results in a considerable savings in money by reducing the number of valves as well as time when converting the sprinkler system to a different system valve and in resetting the system valve. Use of the present invention allows the system to be reactivated relatively quickly and is, therefore, safer than existing systems.